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Masaru KOKUBO
2015 Volume E98.A Issue 2 Pages
459
Published: 2015
Released on J-STAGE: February 01, 2015
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Akihiko KANOUDA, Takayuki OUCHI, Takae SHIMADA
Article type: INVITED PAPER
2015 Volume E98.A Issue 2 Pages
460-465
Published: 2015
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The bidirectional DC-DC converters that are used in backup power supplies, energy storage systems, and electric vehicles, are described in this paper, because they have recently attracted a lot of attention. First, this paper shows the main use of the bidirectional DC-DC converter, the optimum circuit topology in accordance with its use, and the characteristic properties of the circuits. In addition, the expected characteristics for the next generations of power semiconductor devices for each bidirectional converter circuit are shown.
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Yu HOU, Takamoto WATANABE, Masaya MIYAHARA, Akira MATSUZAWA
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
466-475
Published: 2015
Released on J-STAGE: February 01, 2015
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An all-digital time-domain ADC, abbreviated as TAD, is presented in this paper. All-digital structure is intrinsically compatible with the scaling of CMOS technology, and can satisfy the great demand of miniaturized and low-voltage sensor interface. The proposed TAD uses an inverter-based Ring-Delay-Line (RDL) to transform the input signal from voltage domain to time domain. The voltage-modulated time information is then digitized by a composite architecture namely “4-Clock-Edge-Shift Construction” (4CKES). TAD features superior voltage sensitivity and 1st-order noise shaping, which can significantly simplify the power-hungry pre-conditioning circuits. Reconfigurable resolution can be easily achieved by applying different sampling rates. A TAD prototype is fabricated in 65nm CMOS, and consumes a small area of 0.016mm
2. It achieves a voltage resolution of 82.7µV/LSB at 10MS/s and 1.96µV/LSB at 200kS/s in a narrow input range of 0.1Vpp, merely under 0.6V supply. The highest SNR of TAD prototype is 61.36dB in 20kHz bandwidth at 10MS/s. This paper also analyzes the nonideal effects of TAD and discusses the potential solutions. As the principal drawback, nonlinearity of TAD can be compensated by the differential-setup and digital calibration.
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Zule XU, Seungjong LEE, Masaya MIYAHARA, Akira MATSUZAWA
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
476-484
Published: 2015
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We present a time-to-digital converter (TDC) achieving sub-picosecond resolution and high precision for all-digital phase-locked-loops (ADPLLs). The basic idea is using a charge pump to translate time interval into charge, and a successive-approximation-register-analog-to-digital converter (SAR-ADC) to quantize the charge. With this less complex configuration, high resolution, high precision, low power, and small area can be achieved all together. We analyzed the noise contribution from the charge pump and describe detailed design and implementation for sizing the capacitor and transistors, with the awareness of noise and linearity. The analysis demonstrates the proposed TDC capable of sub-picosecond resolution and high precision. Two prototype chips were fabricated in 65nm CMOS with 0.06mm
2, and 0.018mm
2 core areas, respectively. The achieved resolutions are 0.84ps and 0.80ps, in 8-bit and 10-bit range, respectively. The measured single-shot-precisions range from 0.22 to 0.6ps, and from 0.66 to 1.04ps, respectively, showing consistent trends with the analysis. Compared with state-of-the-arts, best performance balance has been achieved.
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Takashi KAWAMOTO, Masato SUZUKI, Takayuki NOTO
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
485-491
Published: 2015
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A serial ATA PHY fabricated in a 0.15-µm CMOS process performs the serial ATA operation in an asynchronous transition by using large variation in the reference clock. This technique calibrates a transmission signal frequency by utilizing the received signal. This is achieved by calibrating the divide ratio of a spread-spectrum clock generator (SSCG). This technique enables a serial ATA PHY to use reference oscillators with a production-frequency tolerance of less than 400ppm, i.e., higher than the permissible TX frequency variations (i.e., 350ppm). The calibrated transmission signal achieved a total jitter of 3.9ps.
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Masanori FURUTA, Hidenori OKUNI, Masahiro HOSOYA, Akihide SAI, Junya M ...
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
492-499
Published: 2015
Released on J-STAGE: February 01, 2015
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This paper presents an analog front-end circuit for a 60-GHz proximity wireless communication receiver. The feature of the proposed analog front-end circuit is a bandwidth more than 1-GHz wide. To expand the bandwidth of a low-pass filter and a voltage gain amplifier, a technique to reduce the parasitic capacitance of a transconductance amplifier is proposed. Since the bandwidth is also limited by on-resistance of the ADC sampling switch, a switch separation technique for reduction of the on-resistance is also proposed. In a high-speed ADC, the SNDR is limited by the sampling jitter. The developed high resolution VCO auto tuning effectively reduces the jitter of PLL. The prototype is fabricated in 65nm CMOS. The analog front-end circuit achieves over 1-GHz bandwidth and 27.2-dB SNDR with 224mW Power consumption.
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Koji KOTANI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
500-507
Published: 2015
Released on J-STAGE: February 01, 2015
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Efficiency of the photovoltaic-assisted UHF CMOS rectifier, which is one example realization of the synergistic ambient energy harvesting concept, has been improved by symmetric PV cell structure. Balanced biasing for the n-channel and p-channel diode-connected MOSFETs realized by the symmetric PV cells effectively compensates Vths and prevents useless leakage current, resulting in the improved efficiency of the rectifier under low input power conditions. In addition, by extending the balanced biasing concept, output-voltage-boosted PV cell structure was proposed and found to be effective for further improving the efficiency of the rectifier. As a result, under a typical indoor lighting condition of 300lx, power conversion efficiency of 25.4% was achieved at -20dBm of 920MHz RF input and 47kΩ output loading conditions, being 3.6 times larger than a conventional rectifier without PV assistance.
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Hayate KOJIMA, Yoshinobu MAEDA, Taishin NOMURA
Article type: LETTER
2015 Volume E98.A Issue 2 Pages
508-509
Published: 2015
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We proposed a hard-wired CPG hardware network to reproduce the gaits of four-legged animals. It should reproduce walking and bounding, and they should be switchable with each other by changing the value of only one voltage.
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Shigenobu SASAKI
2015 Volume E98.A Issue 2 Pages
510
Published: 2015
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Takehiko KOBAYASHI, Miyuki HIROSE
Article type: INVITED PAPER
2015 Volume E98.A Issue 2 Pages
511-519
Published: 2015
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The authors have focused on wideband, including ultra-wideband (UWB, 3.1 to 10.6GHz) radio propagation in various environments, such as a small space-craft and a passenger car, moreover on-body radio propagation measurements have been conducted. Many studies have been reported about indoor propagation for narrowband and wideband. However previous study has not been examined characteristics between 10-MHz and 1-GHz frequencies. In our previous study, UWB and narrowband propagation were measured in a UWB frequency band within closed/semi-closed spaces (e.g. a spacecraft, a passenger car, and a metal desk equipped with a metal partition). While narrowband propagation resulted in considerable spatial variations in propagation gain due to interferences caused by multipath environments, UWB yielded none. This implies that the UWB systems have an advantage over narrowband from a viewpoint of reducing fading margins. Thus, a use of UWB technology within spacecrafts has been proposed with a view to partially replacing wired interface buses with wireless connections. Adoption of wireless technologies within the spacecrafts could contribute to reduction in cable weight (and launching cost as a result), reduction in the cost of manufacture, more flexibility in layout of spacecraft subsystems, and reliable connections at rotary, moving, and sliding joints. Path gains and throughputs were also measured for various antenna settings and polarizations in the small spacecraft. Polarization configurations were found to produce almost no effect on average power delay profiles and substantially small effects on the throughputs. Furthermore, statistical channel models were proposed. Also UWB technologies have been considered for use in wireless body area networks (WBAN) because of their possible low power consumption and anti-multipath capabilities. A series of propagation measurements were carried out between on-body antennas in five different rooms. A new path loss and statistical models considering room volume had been proposed. In this paper, we evaluated propagation characteristics in heavy multipath environments, especially examined the channels at 10-MHz to 1-GHz frequencies.
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Kazuo HAGIHARA, Kouji OHUCHI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
520-527
Published: 2015
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As one of optical wireless Orthogonal Frequency Division Multiplexing (OFDM) systems, there is Flip-OFDM, which separates an OFDM signal into positive and negative parts and transmits them. It has good power efficiency and low hardware complexity. However, the system halves transmission efficiency compared with Direct Current-biased Optical OFDM. In this paper, Circular Polarized Optical OFDM (CPO-OFDM) is presented. This system separates OFDM signals into positive and negative parts, and it converts these signals into left-handed and right-handed polarization, and it multiplexes these signals. CPO-OFDM is analyzed with an intensity modulation/direct detection channel model which considers the change of the state of polarization owing to free space propagation. As a result of the analysis, it is shown that CPO-OFDM is a flexible system like the conventional systems by using circular polarization and it has the equivalent bit error rate (BER) and the double transmission efficiency compared with Flip-OFDM. The IM/DD channel model which considers the degree of polarization (DOP) is also shown. As for the DOP, it improves by the increase of the propagation distance. Thus, we can achieve the equivalent BER obtained with a high DOP laser even if we use a low DOP laser.
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Tatsuya OHTA, Kouji OHUCHI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
528-536
Published: 2015
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A multicode transmission (MC) system can transmit multiple data streams at one time. However, the amplitude of the transmission signal has sharp fluctuations. To avoid this problem, constant amplitude (CA) signaling schemes were studied, and some MC systems were developed such as the MC system with CA signaling (MC-CA) and the parallel combinatory MC system with CA signaling (PCMC-CA). In this paper, extension systems of PCMC-CA system are developed. In particular, two demodulation methods are discussed for the extension systems. Then, the bit error rate (BER) and data transmission rate are theoretically analyzed. The results shows that the extension systems has a better performance than the MC-CA system in both of the BER and data transmission rate.
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Junichiro HAGIWARA
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
537-548
Published: 2015
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This paper proposes a novel scheme for sequential orthogonal frequency division multiplexing channel estimation on the receiver side.The scheme comprises two methods: one improves estimation accuracy and the other reduces computational complexity. Based on a state-space model, the first method appropriately considers frequency correlation in an approach that derives a narrow-band channel gain for multiple pilot subcarriers; such consideration of frequency correlation leads to an averaging effect in the frequency domain. The second method is based on the first one and forces the observation matrix into a sparse bidiagonal matrix in order to decrease the number of mathematical processes. The proposed scheme is verified by numerical analysis.
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Shuhei HORIO, Keigo TAKEUCHI, Tsutomu KAWABATA
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
549-557
Published: 2015
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For low-density parity-check codes, spatial coupling was proved to boost the performance of iterative decoding up to the optimal performance. As an application of spatial coupling, in this paper, bit-interleaved coded modulation (BICM) with spatially coupled (SC) interleaving — called SC-BICM — is considered to improve the performance of iterative channel estimation and decoding for block-fading channels. In the iterative receiver, feedback from the soft-in soft-out decoder is utilized to refine the initial channel estimates in linear minimum mean-squared error (LMMSE) channel estimation. Density evolution in the infinite-code-length limit implies that the SC-BICM allows the receiver to attain accurate channel estimates even when the pilot overhead for training is negligibly small. Furthermore, numerical simulations show that the SC-BICM can provide a steeper reduction in bit error rate than conventional BICM, as well as a significant improvement in the so-called
waterfall performance for high rate systems.
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Ou ZHAO, Hidekazu MURATA
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
558-568
Published: 2015
Released on J-STAGE: February 01, 2015
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The performance of multiuser multiple-input single-output (MU-MISO) systems is not only affected by small-scale multipath fading but also by large-scale fading (i.e., shadowing) and path loss. In this paper, we concentrate on the sum rate distribution of MU-MISO systems employing linear zero-forcing beamforming, accounting for both multipath fading and shadowing effects, as well as spatial correlation at the transmit and receiver sides. In particular, we consider the classical spatially correlated lognormal model and propose closed-form bounds on the distribution of the achievable sum rates in MU-MISO systems. With the help of these bounds, we derive a relationship between the interuser distance and sum rate corresponding to 10% of the cumulative distribution function under different environmental conditions. A practical conclusion from our results based on the considered system is that the effect of spatially correlated shadowing can be considered to be independent when the interuser distance is approximately five times the shadowing correlation distance. Furthermore, a detailed analysis of the effects of composite channel attenuation consisting of multipath fading and shadowing is also provided.
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Shuta KAKO, Osamu TAKYU, Takeo FUJII
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
569-577
Published: 2015
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In this paper, we propose a secondary user (SU) resource assignment algorithm for a multi-hop (MH) cognitive radio network to improve the end-to-end throughput. In the MH networks used for spectrum sharing, each SU needs to improve the throughput by taking the primary user (PU) protection into account. For overcoming this problem, we estimate the PU acceptable received power, which is determined by the acknowledgment packet (ACK) power from the PU receiver at each SU. With this estimation, we propose an SU optimal transmit power control algorithm to not only maximize the end-to-end throughput of the SU MH flow but also maintain the considered PU acceptable interference power. In this study, a distributed joint allocation algorithm has been used to solve the optimization problem and to effectively allocate the power of each SU.
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Fumihiro INOUE, Takayuki NISHIO, Masahiro MORIKURA, Koji YAMAMOTO, Fus ...
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
578-588
Published: 2015
Released on J-STAGE: February 01, 2015
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The problem of coexistence between IEEE 802.11g based wireless LANs (WLANs) and IEEE 802.15.4 based wireless personal area networks (WPANs) in the 2.4GHz band is an important issue for the operation of a home energy management system (HEMS) for smart grids. This paper proposes a coexistence scheme that is called a Hybrid station aided coexistence (HYSAC) scheme to solve this problem. This scheme employs a hybrid-station (H-STA) that possesses two types of network device functions. The scheme improves the data transmission quality of the WPAN devices which transmit energy management information such as power consumption. The proposed HYSAC scheme employs WLAN control frames, which are used to assign WPAN system traffic resources. Moreover, we propose a coexistence method to achieve excellent WLAN throughput where multiple WPANs coexist with a WLAN. We theoretically derive the performance of the proposed scheme by considering the QoS support in WLAN and show that the results of the simulation and theoretical analysis are in good agreement. The numerical results show that the HYSAC scheme decreases the beacon loss rate of WPAN to less than 1% when the WLAN system consists of 10 STAs under saturated traffic conditions. Furthermore, the WLAN throughput of the proposed synchronization method is shown to be 30.6% higher than that of the HYSAC scheme without synchronization when the WLAN that consists of 10 STAs coexists with four WPANs.
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Kazuki SUGENO, Yukitoshi SANADA, Mamiko INAMORI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
589-596
Published: 2015
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In recent years, wireless power transfer has been attracting a great deal of attention. In order to realize efficient power transfer, it is necessary to communicate data such as a frequency, required power, or error tolerance. In the proposed system, because of the use of the same antennas for power transmission and data transmission, the frequency response of a channel for the data transmission changes owing to load fluctuation and the distance between antennas. This paper investigates data transmission performance in the wireless power transfer system with frequency response estimation at the transmitter side. The numerical results obtained through computer simulation show that the proposed scheme can estimate the frequency response of the channel and the difference between the expected bit error rate (BER) and the BER with the estimation error is less than 0.5dB at the BER of 10
-3.
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Hiroyuki HATANO, Masahiro FUJII, Atsushi ITO, Yu WATANABE, Yusuke YOSH ...
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
597-605
Published: 2015
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We focus on forward-looking radar network systems for automotive usages. By using multiple radars, the radar network systems will achieve reliable detection and wide observation area. The forward-looking systems by cameras are famous. In order to realize more reliable safety, the cameras had better be used with other sensing devices such as the radar network. In the radar network, processing of the data, which is derived from the multiple receivers, is important because the processing decides the estimation performance. In this paper, we will introduce our estimation algorithm which focuses on target existence probability and virtual receivers. The performance will be evaluated by simulated targets which are both single point model and 3D target model.
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Satoshi NISHINO, Hidekazu MURATA
Article type: LETTER
2015 Volume E98.A Issue 2 Pages
606-610
Published: 2015
Released on J-STAGE: February 01, 2015
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We consider user selection schemes for multi-user MIMO systems with linear precoding. In this work, we apply two user selection schemes based on the orthogonality between the propagation channel of MSs. Indoor transmission experiments are carried out under several scenarios and the performances of user selection schemes are evaluated. It is shown that the transmission performance is improved and the user selection schemes are remarkably affected by the path loss between MSs.
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Masaki NAKAMURA
2015 Volume E98.A Issue 2 Pages
611
Published: 2015
Released on J-STAGE: February 01, 2015
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Yoshiyuki SAKAMAKI, Toshiaki TANAKA, Hisashi YAMADA, Toshio SUGIHARA
Article type: INVITED PAPER
2015 Volume E98.A Issue 2 Pages
612-617
Published: 2015
Released on J-STAGE: February 01, 2015
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In elevator-group control, the average number of running cars should be finely adjusted by the dynamically controlling the number of running cars (DCNRC). Traffic demand in an office building varies throughout the day. In this paper, we propose a new energy-saving method for elevator-group control that adjusts the number of running cars according to the traffic demand, simulate the proposed energy-saving method under nearly real traffic demand conditions of an office building, and reduce the daily energy consumption to the target level after several days.
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Miwa YOSHIMOTO, Koichi KOBAYASHI, Kunihiko HIRAISHI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
618-625
Published: 2015
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In this paper, we present a new method for diagnosis of stochastic discrete event system. The method is based on anomaly detection for sequences. We call the method
sequence profiling (SP). SP does not require any system models and any system-specific knowledge. The only information necessary for SP is event logs from the target system. Using event logs from the system in the normal situation,
N-gram models are learned, where the
N-gram model is used as approximation of the system behavior. Based on the
N-gram model, the diagnoser estimates what kind of faults has occurred in the system, or may conclude that no faults occurs. Effectiveness of the proposed method is demonstrated by application to diagnosis of a multi-processor system.
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Koichi KOBAYASHI, Takuro NAGAMI, Kunihiko HIRAISHI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
626-634
Published: 2015
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In this paper, optimal control of multi-vehicle systems is studied. In the case where collision avoidance between vehicles and obstacle avoidance are imposed, state discretization is effective as one of the simplified approaches. Furthermore, using state discretization, cooperative actions such as rendezvous can be easily specified by linear temporal logic (LTL) formulas. However, it is not necessary to discretize all states, and partial states (e.g., the position of vehicles) should be discretized. From this viewpoint, a new control method for multi-vehicle systems is proposed in this paper. First, the system in which partial states are discretized is formulated. Next, the optimal control problem with constraints described by LTL formulas is formulated, and its solution method is proposed. Finally, numerical simulations are presented. The proposed method provides us a useful method in control of multi-vehicle systems.
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Ichiro TOYOSHIMA, Shingo YAMAGUCHI, Yuki MURAKAMI
Article type: PAPER
2015 Volume E98.A Issue 2 Pages
635-644
Published: 2015
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A workflow net (WF-net for short) is a Petri net which represents a workflow. There are two important subclasses of WF-nets: extended free choice (EFC for short) and well-structured (WS for short). It is known that most actual workflows can be modeled as EFC WF-nets; and acyclic WS is a subclass of acyclic EFC but has more analysis methods. A sound acyclic EFC WF-net may be transformed to an acyclic WS WF-net without changing the observable behavior of the net. Such a transformation is called refactoring. In this paper, we tackled a problem, named acyclic EFC WF-net refactorizability problem, that decides whether a given sound acyclic EFC WF-net is refactorable to an acyclic WS WF-net. We gave two sufficient conditions on the problem, and constructed refactoring procedures based on the conditions. Furthermore, we applied the procedures to a sample workflow, and confirmed usefulness of the procedures for the enhancement of the readability and the analysis power of acyclic EFC WF-nets.
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Supacheep AMTADE, Toshiyuki MIYAMOTO
Article type: LETTER
2015 Volume E98.A Issue 2 Pages
645-649
Published: 2015
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A cloud system is defined as a large scale computer system that contains running high performance computers and responds to a large number of incoming tasks over the Internet. In this paper, we consider the problem to schedule computational jobs efficiently regarding system resource constraint and introduce a cuckoo search (CS) algorithm. Experimental results show that CS outperforms the genetic algorithm in terms of fitness value.
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Takashi YAMAMOTO, Shigemasa TAKAI
Article type: LETTER
2015 Volume E98.A Issue 2 Pages
650-653
Published: 2015
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In this paper, we consider a decentralized failure diagnosis problem for discrete event systems. For a conjunctively codiagnosable system, there exists a conjunctive decentralized diagnoser that can detect the occurrence of any failure within a uniformly bounded number of steps. We present a method for synthesizing such a conjunctive decentralized diagnoser as an online diagnoser.
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Seokjin LEE, Hee-Suk PANG
Article type: PAPER
Subject area: Digital Signal Processing
2015 Volume E98.A Issue 2 Pages
654-664
Published: 2015
Released on J-STAGE: February 01, 2015
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Recently, array speaker products have received attention in the field of consumer electronics, and control technologies for arrayed speaker units, including beamforming and wave field synthesis (WFS), have been developed for various purposes. An important application of these algorithms is focused source reproduction. The focused source reproduction capability is strongly coupled with the array length. The array length is a very important design factor in consumer products, but it is very short in home entertainment systems, compared with ideal WFS systems or theater speaker systems. Therefore, a well-defined measure for the maximum focusing range is necessary for designing an array speaker product. In this paper, a maximum focusable range measure is proposed and is analyzed by simulation of a small array speaker. The analysis results show that the proposed maximum focusable range has properties strongly related to the capability for focused source reproduction.
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Takashi OSHIMA, Taizo YAMAWAKI
Article type: PAPER
Subject area: Analog Signal Processing
2015 Volume E98.A Issue 2 Pages
665-675
Published: 2015
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Novel deterministic digital calibration of pipelined ADC has been proposed and analyzed theoretically. Each MDAC is dithered exploiting its inherent redundancy during the calibration. The dither enables fast accurate convergence of calibration without requiring any accurate reference signal and hence with minimum area and power overhead. The proposed calibration can be applied to both the 1.5-bit/stage MDAC and the multi-bit/stage MDAC. Due to its simple structure and algorithm, it can be modified to the background calibration easily. The effectiveness of the proposed calibration has been confirmed by both the extensive simulations and the measurement of the prototype 0.13-µm-CMOS 50-MS/s pipelined ADC using the op-amps with only 37-dB gain. As expected, SNDR and SFDR have improved from 35.5dB to 58.1dB and from 37.4dB to 70.4dB, respectively by the proposed calibration.
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Rui HOU, Tingting HE, Mingming ZHENG, Tengyue MAO
Article type: PAPER
Subject area: Systems and Control
2015 Volume E98.A Issue 2 Pages
676-683
Published: 2015
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In this paper, we propose a controlled retransmission scheme in optical burst switching (OBS) networks. Different from previous works in the literature, we set a different value to retransmission probability at each contention and propose a retransmission analytical model for burst segmentation contention resolution scheme. In addition, we consider the effect of relevance in traffic come from multiple paths. We take into account the load at each link (include the given links and the other correlated links taking traffic) due to both the fresh and the retransmitted traffic and calculate the path blocking probability and the byte loss probability (ByLP) in cases of without and with full- wavelength conversion to evaluate the network performance. An extensive simulation is proposed to validate our analytical model, and results have shown that both path blocking probability and ByLP are affected by the load and the retransmission probability in each contention along a path and the correlated traffic carried links on the path.
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Masato IZAWA, Hiroyuki TORIKAI
Article type: PAPER
Subject area: Nonlinear Problems
2015 Volume E98.A Issue 2 Pages
684-699
Published: 2015
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The mammalian cochlear consists of highly nonlinear components: lymph (viscous fluid), a basilar membrane (vibrating membrane in the viscous fluid), outer hair cells (active dumpers for the basilar membrane), inner hair cells (neural transducers), and spiral ganglion cells (parallel spikes density modulators). In this paper, a novel spiral ganglion cell model, the dynamics of which is described by an asynchronous cellular automaton, is presented. It is shown that the model can reproduce typical nonlinear responses of the spiral ganglion cell in the mammalian cochlea, e.g., spontaneous spiking, parallel spike density modulation, and adaptation. Also, FPGA experiments validate reproductions of these nonlinear responses.
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Yuji KOGUMA, Eitaro AIYOSHI
Article type: PAPER
Subject area: Numerical Analysis and Optimization
2015 Volume E98.A Issue 2 Pages
700-709
Published: 2015
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In Recent years, a paradigm of optimization algorithms referred to as “meta-heuristics” have been gaining attention as a means of obtaining approximate solutions to optimization problems quickly without any special prior knowledge of the problems. Meta-heuristics are characterized by flexibility in implementation. In practical applications, we can make use of not only existing algorithms but also revised algorithms that reflect the prior knowledge of the problems. Most meta-heuristic algorithms lack mathematical grounds, however, and therefore generally require a process of trial and error for the algorithm design and its parameter adjustment. For one of the resolution of the problem, we propose an approach to design algorithms with mathematical grounds. The approach consists of first constructing a “framework” of which dynamic characteristics can be derived theoretically and then designing concrete algorithms within the framework. In this paper, we propose such a framework that employs two following basic strategies commonly used in existing meta-heuristic algorithms, namely, (1) multipoint searching, and (2) stochastic searching with pseudo-random numbers. In the framework, the update-formula of search point positions is given by a linear combination of normally distributed random numbers and a fixed input term. We also present a stability theory of the search point distribution for the proposed framework, using the variance of the search point positions as the index of stability. This theory can be applied to any algorithm that is designed within the proposed framework, and the results can be used to obtain a control rule for the search point distribution of each algorithm. We also verify the stability theory and the optimization capability of an algorithm based on the proposed framework by numerical simulation.
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Amin JAMALI, Mehdi BERENJKOUB, Hossein SAIDI
Article type: PAPER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
710-720
Published: 2015
Released on J-STAGE: February 01, 2015
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Autonomous ad hoc networks are networks with nodes belonging to different authorities, and cooperative behavior of nodes is not guaranteed in such networks. In this paper, defense mechanisms are introduced to protect nodes against injecting traffic attacks in an autonomous ad hoc network, and to stimulate nodes to forward packets for each other. We have a cross-layer approach in the design of our mechanisms, and nodes use information from medium access control (MAC) layer for selecting a good route. In addition, nodes attempt to drop packets of those nodes that violate MAC layer backoff mechanism. Analytical and simulation results demonstrate the effectiveness of our proposed mechanisms in the presence of injecting traffic attacks and MAC layer misbehaviors in an ad hoc network that consists of selfish nodes.
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Hui LI, Liang YUAN
Article type: PAPER
Subject area: Measurement Technology
2015 Volume E98.A Issue 2 Pages
721-734
Published: 2015
Released on J-STAGE: February 01, 2015
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Least squares error (LSE) method adopted recursively can be used to track the frequency and amplitude of signals in steady states and kinds of non-steady ones in power system. Taylor expansion is used to give another version of this recursive LSE method. Aided by variable-windowed short-time discrete Fourier transform, recursive LSEs with and without Taylor expansion converge faster than the original ones in the circumstance of off-nominal input singles. Different versions of recursive LSE were analyzed under various states, such as signals of off-nominal frequency with harmonics, signals with step changes, signals modulated by a sine signal, signals with decaying DC offset and additive Gaussian white noise. Sampling rate and data window size are two main factors influencing the performance of method recursive LSE in transient states. Recursive LSE is sensitive to step changes of signals, but it is in-sensitive to signals' modulation and singles with decaying DC offset and noise.
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Jangyong PARK, Yunho JUNG, Jaeseok KIM
Article type: LETTER
Subject area: Digital Signal Processing
2015 Volume E98.A Issue 2 Pages
735-739
Published: 2015
Released on J-STAGE: February 01, 2015
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In this letter, we propose a low complexity fixed sphere decoder (FSD) with statistical threshold for multiple-input and multiple-output (MIMO) systems. The proposed algorithm is developed by applying two threshold-based pruning algorithms using an initial detection and statistical noise constraint to the FSD. The proposed FSD algorithm is suitable for a fully pipelined hardware implementation and also has low complexity because the threshold of the proposed pruning algorithm is pre-calculated and independently applied to the path without sorting operation. Simulation results show that the proposed FSD has the performance of the original FSD as well as a low complexity compared to the original FSD and other low complexity FSD algorithms.
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Hyun-Jun SHIN, Jung-In BAIK, Hyoung-Kyu SONG
Article type: LETTER
Subject area: Digital Signal Processing
2015 Volume E98.A Issue 2 Pages
740-744
Published: 2015
Released on J-STAGE: February 01, 2015
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In wireless communication, it is hard to set the optimal route between a source and a destination through relays, since for optimal relaying, the system operator should know all channel conditions from a source to a destination through relays and determine the path with all channel conditions. In this letter, a multiple relay selection strategy is proposed for the reliability of transmission. The proposed strategy establishes a relaying route to a destination and provides an efficient relay selection process regardless of all channel conditions.
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Yan Shen DU, Ping WEI, Hua Guo ZHANG, Hong Shu LIAO
Article type: LETTER
Subject area: Digital Signal Processing
2015 Volume E98.A Issue 2 Pages
745-748
Published: 2015
Released on J-STAGE: February 01, 2015
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In this work, the differential received signal strength based localization problem is addressed. Based on the measurement model, we present the constrained weighted least squares (CWLS) approach, which is difficult to be solved directly due to its nonconvex nature. However, by performing the semidefinite relaxation (SDR) technique, the CWLS problem can be relaxed into a semidefinite programming problem (SDP), which can be efficiently solved using modern convex optimization algorithms. Moreover, the SDR is proved to be tight, and hence ensures the corresponding SDP find the optimal solution of the original CWLS problem. Numerical simulations are included to corroborate the theoretical results and promising performance.
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Yanzi ZHOU, Ryo TAKAHASHI, Takashi HIKIHARA
Article type: LETTER
Subject area: Systems and Control
2015 Volume E98.A Issue 2 Pages
749-753
Published: 2015
Released on J-STAGE: February 01, 2015
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In this letter, we establish a model of a digital clock synchronization method for power packet dispatching. The first-order control is carried out to a specified model to achieve the clock synchronization. From the experimental results, it is confirmed that power packets were recognized under autonomous synchronization.
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Yu ZHANG, Songfeng LU, Hua ZHAO
Article type: LETTER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
754-757
Published: 2015
Released on J-STAGE: February 01, 2015
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Up until now, the best public key encryption with multi-dimensional range query (PKMDRQ) scheme has two problems which need to be resolved. One is that the scheme is selectively secure. The other is that the time of decryption is long. To address these problems, we present a method of converting a predicate encryption supporting inner product (IPE) scheme into a PKMDRQ scheme. By taking advantage of this approach, an instance is also proposed. The comparison between the previous work and ours shows that our scheme is more efficient over the time complexity. Moreover, our scheme is adaptively secure.
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Xiaoming HU, Yinchun YANG, Jian WANG, Huajie XU, Wenan TAN
Article type: LETTER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
758-761
Published: 2015
Released on J-STAGE: February 01, 2015
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Presently, many identity-based proxy signature (IBPS) schemes have been proposed, but most of them require high computational costs and the proposed security model for IBPS is not enough complete. To overcome this weakness, Gu et al. recently proposed a framework and a detailed security model for IBPS. They also proposed an efficient IBPS scheme and proved the unforgeability of their scheme in the standard model. However, in this letter, we demonstrate that Gu et al.'s scheme fails to satisfy the property of unforgeability because it can not resist the following attacks: after getting a private key, an adversary behaving as a malicious signer can forge a private key on any identity without the help of the private key generator (PKG); after getting a delegation, an adversary behaving as a malicious proxy signer can forge a proxy signing key on any delegation without the agreement of the original signer; after getting a signature, an adversary behaving as a malicious user can forge a signature on any identity without the private key or forge a proxy signature on any warrant without the proxy signing key.
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Fei TANG, Hongda LI, Jinyong CHANG
Article type: LETTER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
762-766
Published: 2015
Released on J-STAGE: February 01, 2015
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In a proxy re-encryption (PRE) scheme, a delegator gives a re-encryption key to a semi-trusted proxy, then the proxy can transform the delegator's ciphertexts into one that can be decrypted by a delegatee who is appointed by the delegator. The proxy cannot, however, learn anything about the encrypted messages. At CCS 2007, Canetti and Hohenberger left an interesting open problem of how to design a PRE scheme that is simultaneously unidirectional and multi-hop. This is a rather interesting problem since in some applications we may need this feature, such as in the scenario of email forwarding, a delegatee wants forward his emails that received from the delegator to another delegatee. In this work we design an unidirectional and multi-hop PRE scheme by using multilinear maps. A shortcoming of our scheme is that its security relies on some rather strong assumptions in the setting of multilinear groups.
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Maki YOSHIDA, Toru FUJIWARA
Article type: LETTER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
767-770
Published: 2015
Released on J-STAGE: February 01, 2015
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A secret sharing scheme is said to be
d-multiplicative if the scheme allows the players to multiply shared
d secrets by locally converting their shares into an additive sharing of the product. In the previous work, the following negative result for perfect secret sharing has been shown: The
d-multiplicative secret sharing for
d players is impossible. This paper extends the impossibility result to non-perfect secret sharing. Our main result is a proof that
d-multiplicative secret sharing for
d players is impossible even if every player has partial information on the secret (e.g., all but one bit). This result means that there is no need to relax the privacy requirement with leakage of partial information only for the purpose of
d-multiplication.
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Tongjiang YAN, Huadong LIU, Yuhua SUN
Article type: LETTER
Subject area: Cryptography and Information Security
2015 Volume E98.A Issue 2 Pages
771-775
Published: 2015
Released on J-STAGE: February 01, 2015
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In this paper, we modify the Legendre-Sidelnikov sequence which was defined by M. Su and A. Winterhof and consider its exact autocorrelation values. This new sequence is balanced for any
p,
q and proved to possess low autocorrelation values in most cases.
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Zhiting YAN, Guanghui HE, Weifeng HE, Zhigang MAO
Article type: LETTER
Subject area: Communication Theory and Signals
2015 Volume E98.A Issue 2 Pages
776-782
Published: 2015
Released on J-STAGE: February 01, 2015
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Co-channel interference (CCI) is becoming a challenging factor that causes performance degradation in modern communication systems. The receiver equipped with multiple antennas can suppress such interference by exploiting spatial correlation. However, it is difficult to estimate the spatial covariance matrix (SCM) of CCI accurately with limited number of known symbols. To address this problem, this paper first proposes an improved SCM estimation method by shrinking the variance of eigenvalues. In addition, based on breadth-first tree search schemes and improved channel updating, a low complexity iterative detector is presented with channel preprocessing, which not only considers the existence of CCI but also reduces the computational complexity in terms of visited nodes in a search tree. Furthermore, by scaling the extrinsic soft information which is fed back to the input of detector, the detection performance loss due to max-log approximation is compensated. Simulation results show that the proposed iterative receiver provides improved signal to interference ratio (SIR) gain with low complexity, which demonstrate the proposed scheme is attractive in practical implementation.
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Masaki TAKANASHI, Satoshi MAKIDO
Article type: LETTER
Subject area: Intelligent Transport System
2015 Volume E98.A Issue 2 Pages
783-787
Published: 2015
Released on J-STAGE: February 01, 2015
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Providing images captured by an on-board camera to surrounding vehicles is an effective method to achieve smooth road traffic and to avoid traffic accidents. We consider providing images using WiFi technology based on the IEEE802.11p standard for vehicle-to-vehicle (V2V) communication media. We want to compress images to suppress communication traffic, because the communication capacity of the V2V system is strictly limited. However, there are difficulties in image compression and transmission using wireless communication especially in a vehicular broadcast environment, due to transmission errors caused by fading, packet collision, etc. In this letter, we propose an image transmission technique based on compressed sensing. Through computer simulations, we show that our proposed technique can achieve stable image reconstruction despite frequent packet error.
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Hao ZHANG, Mengtian RONG, Tao LIU
Article type: LETTER
Subject area: Image
2015 Volume E98.A Issue 2 Pages
788-791
Published: 2015
Released on J-STAGE: February 01, 2015
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In this letter, we propose a new intra-field deinterlacing algorithm based on an edge dependent weighted filter (EDWF). The proposed algorithm consists of three steps: 1) calculating the gradients of three directions (45°, 90°, and 135°) in the local working window; 2) achieving the weights of the neighboring pixels by exploiting the edge information in the pixel gradients; 3) interpolating the missing pixel using the proposed EDWF interpolator. Compared with existing deinterlacing methods on different images and video sequences, the proposed algorithm improves the peak signal-to-noise-ratio (PSNR) while achieving better subjective quality.
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Akira TAGUCHI, Yoshikatsu HOSHI
Article type: LETTER
Subject area: Image
2015 Volume E98.A Issue 2 Pages
792-795
Published: 2015
Released on J-STAGE: February 01, 2015
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While emphasizing the intensity or saturation component for getting high-quality color images, keeping the hue component unchanged is important; thus, perceptual color models such as HSI and HSV have been used. Hue-Saturation-Intensity (HSI) is a public color model, and many color applications are commonly based on this model. However, the transformation from the HSI color space to the RGB color space after processing intensity/saturation in the HSI color space usually generates the gamut problem. In this study, we clear the relationship between the RGB gamut and the HSI gamut completely. According to the result, we can check whether the processing result is located inside or outside of the RGB gamut without transforming to the RGB color space. If the processing result is judged outside of the RGB gamut, we apply the effective way of hue preserving correction algorithm which is proposed in this study to the saturation component. Experimental results demonstrate that the proposed algorithm can correct the color distortion caused by the enhancement without reducing the visual effect and it is especially useful for images with rich colors and local high component values.
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Shi BAO, Go TANAKA
Article type: LETTER
Subject area: Image
2015 Volume E98.A Issue 2 Pages
796-800
Published: 2015
Released on J-STAGE: February 01, 2015
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A new signed color distance for color-to-gray conversion is proposed. It is suited to reflect gradation and detailed color change in an input color image into an output monochrome image. Experiments show the effectiveness of the proposed distance.
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